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Protel is a well-known Electronic Design Automation (EDA) software.

Schematic diagram

Protel is a well-known Electronic Design Automation (EDA) software, and its file types are as follows (protel99):

Project file .DDB

Schematic file .SCH

PCB file .PCB

The custom library file is generally .LIB

There are also files generated by some functions such as signal integrity check.

Supplementary channel

SCH (Supplemental Channel)

The FCH channel must be used. Only when the FCH channel cannot meet the requirements will the SCH channel be applied.

It depends on the resource situation at that time (CE, Walsh code, etc.) for the SCH with multiple speeds. Up to 16X SCH can be used. That is, the highest theoretical downlink rate is:


Because there are retransmissions and other overhead bits, the actual rate will definitely decrease.

Synchronization channel

SCH (Synchronization Channel)

After the FCCH is decoded, the MS then has to decipher the SCH channel message. The decoded information gives all the messages that the MS needs to synchronize and the cell's TDMA frame number (22bit) and base station identification code BSIC number (6bit).

FCCH and SCH are used to keep MS and BTS synchronized.  When the phone is turned on, the channels that are synchronized in sequence are: FCCH, SCH, BCCH.


Schematic means drawings, diagrams, overviews, and can also be said to be an abbreviation for circuit schematics.

Wall thickness

The classification of steel pipe wall thickness is different in different standards. But there are three main methods of representation.

Tube table number

This is stipulated by the American National Standards Institute ANSIB36.10 (welded and seamless steel pipe) standard in 1938.

The tube table number (Sch.) is the ratio of the design pressure to the allowable stress of the material at the design temperature multiplied by 1000, and is rounded

Rounded value. which is

Sch .=P/[ó]t×1000 (1-2-1)

Where P—design pressure, MPa;

[ó]t—Allowable stress of material at design temperature, MPa.

The pipe table numbers of seamless steel pipes and welded steel pipes can be determined by checking the data.

The tube table numbers in ANSI B36.10 and JIS standards are: Schl0, 20, 30, 40, 60, 80, 100, 120, 140, 160.

The table numbers of the stainless steel pipes in ANSI B36.19 are: 5S, 10S, 40S, 80S.

The tube table number (Sch.) is not a wall thickness but a wall thickness series. Actual wall thickness, same pipe diameter, in different pipe table

The thickness varies in the number. The wall thickness of different tube table numbers is used in the United States and Japan to calculate the thickness of thin-walled tubes subjected to internal pressure

The Barlow formula is determined after calculating and considering the corrosion margin and the negative deviation of the thread depth and wall thickness of -12.5%, as in the formula

(1-2-2) and (1-2-3) are shown. tB=D0P/2[ó]t (1-2-2)

t=[D0/2 (1-0.125)×P/[ó]t]+2.54 (1-2-3)

Where tB t——represents the theoretical and calculated wall thickness, mm

D0————Outer diameter of tube, mm

P——Design pressure, MPa

[ó]t——Allowable pressure of material at design temperature, MPa

The actual wall thickness is calculated after the wall thickness diameter is rounded.

If the pipe table number of the steel pipe is known, the design pressure that the steel pipe can adapt to can be calculated according to formula (1-2-1), namely

P=Sch..× [ó]t/1000 (1-2-4)

For example, the stock Sch40, carbon steel 20 seamless steel pipe, when the design temperature is 350oC, the steel pipe can adapt to the design pressure:

P=40×92/1000①=3.68 MPa

The standard of China Petrochemical Corporation SHJ405 specifies the wall thickness series of seamless steel tubes and Sch. 5S②, Sch. 10,

Sch. 10s, Sch. 20, Sch. 20s, Sch. 30, Sch. 40, Sch. 40s, Sch. 60, Sch. 80, Sch. 100,

Sch. 120, Sch. 140, Sch. 160, as shown in Table 1-2-9.

Tube weight

The method of expressing the wall thickness in terms of pipe weight as specified by the US MSS and ANSI divides the pipe wall thickness into three types:

(1) The standard weight tube is represented by STD;

(2) The thickened tube is represented by XS;

(3) Extra thick pipes are indicated by XXS.

<DN250mm tube, Sch40 is equivalent to STD tube.

<DN200mm tube, Sch80 is equivalent to XS tube.

Wall thickness

Some steel pipe standards in China, ISO and Japan use the wall thickness dimension to represent the series of steel pipe wall thickness. For example: the wall thickness of welded steel pipes for low-pressure fluid transportation in my country is divided into ordinary pipes and reinforced pipes, for welded steel pipes for fluid transportation; SGP and STPY welded steel pipe series of Japanese JIS standards only specify the actual thickness series. The method for expressing the specifications of this type of steel pipe is the outer diameter of the pipe × wall thickness. For example, ф60.5×3.8.


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